Adjustable output power supplies are commonly required in a wide variety of industrial applications, specifically to control the operation of an AC motor. Common prior art practice has been to create a two-portion drive, having an input portion to convert AC to DC and an output portion converting DC to adjustable AC. Both the AC to DC and the DC to AC portions of the drive will typically use solid state switching components. FIG. 1A shows a typical current source drive circuit. Such current source drives have three main disadvantages versus Pulse Width Modulated (PWM) voltage source drives; namely common mode output voltage, input harmonics, and variable input power factor. Of these disadvantages, the common mode output voltage may be the most critical, because its solution has traditionally required either a full rated input transformer or special motor insulation. These solutions can be expensive in both the cost of the additional equipment and in the physical space requirements associated with full rated transformers. FIG. 1a shows a typical current source drive circuit, a six-pulse rectifier converts three phase AC power from a utility to DC current. The neutral of the utility is usually grounded. This DC current flows through an inductor to a second converter (DC to AC), where it is converted back into three phase AC at a different or varying frequency. When the semiconductor switches are fired in either the input or output converters, there is a step change of voltage across the DC inductor. Even when the inductor is divided equally between the positive and negative paths as shown in FIG. 1a, half of the step change in voltage appears between the input and output neutrals. Since the input neutral is grounded, the entire voltage appears between the motor windings and ground. This voltage is called "common-mode" because it appears equally in all three output phases. In practice it increases the stress on the motor winding insulation. In some instances, the peak common-mode voltage can equal the peak line-to-neutral output voltage, which doubles the line-to-ground voltage on the motor. Two prior solutions to deal with the common-mode voltage are to increase the motor insulation to protect against the winding to ground, common-mode voltage; or to supply a full KVA rated input isolation transformer, which allows the input neutral to support the voltage. The problem in utilizing this type of drive with existing or older motors is that the option of increasing the motor insulation is not readily available. Utilizing full rated isolation transformers on the input provides the necessary common voltage isolation, but can be quite costly and requires additional space and maintenance for the transformer. While utilization of this type of drive with new motors can be effective if higher rated insulation is applied through the motors when purchased, this increases the cost of the motor, and does not reduce the common-mode voltage and its potential disadvantages. Because in certain configurations the above-described drive may have significant operating and cost advantages, it would be desirable to eliminate or greatly reduce the common-mode voltage at a minimum cost in this type of drive.